WASHINGTON, Sept 13 (Reuters) - U.S. athletic footwear manufacturer New Balance said on Thursday that it pressed the top U.S. trade official during a visit to its Norridgewock, Maine, factory to maintain tariffs on shoes from Vietnam in a proposed free-trade deal.

Only 3,000 workers still make footwear in the United States, with about 1,350 of them employed by New Balance, headquartered in Boston, company spokesman Matt LeBretton told Reuters by phone after the meeting with U.S. Trade Representative Ron Kirk.

The proposed Trans-Pacific Partnership pact between the United States, Vietnam and nine other countries in the region threatens these manufacturing jobs by potentially eliminating tariffs ranging from 8 percent to 37.5 percent on Vietnamese shoes, LeBretton said.

Vietnam is a major clothing and shoe exporter and is looking to increase sales in the United States as a result of the pact.

New Balance wants Washington to maintain tariffs on roughly 20 categories of athletic shoes from Vietnam.

LeBretton said that at the meeting with Kirk, a New Balance employee asked, 'Can you tell us right now you're going to protect our jobs through this free-trade agreement?'"

The 14th round of negotiations on the Trans-Pacific Partnership pact are underway this week in Leesburg, Virginia.

A final deal is not expected until at least 2013. But U.S. officials said this week that the negotiations were entering a more difficult phase in which countries will be grappling with the most politically sensitive issues.

"Our negotiators are working to get a strong deal for American workers and businesses, and we intend to negotiate a high-standard agreement that supports and retains American jobs," Kirk said in a statement released by New Balance.

A second U.S. trade official said the United States generally seeks to eliminate all tariffs in trade agreements, but has responded to specific industry concerns in the past with long phase-out periods and trade-adjustment help.

LeBretton sounded a hopeful note after Kirk's visit.

"We're certainly encouraged by his visit today that (the) USTR is hearing what we say," LeBretton said.